183 research outputs found
Mean, tidal, and fluctuating winds in the middle atmosphere and lower thermosphere observed during MAP/WINE in Northern Scandinavia
During the MAP/WINE campaign in winter 1983 to 1984 several instrumental techniques, such as meteorological rockets, sounding rockets, MST radar and incoherent scatter radar, were applied to measure wind velocities in the middle atmosphere. Profiles of mean, tidal and fluctuating wind velocities were obtained up to 90 to 100 km altitude. These are compared with profiles from models, measurements at other locations and at other times as well as satellite derived data. The results are discussed in terms of ageostropic winds, planetary waves, tidal modes and the possibility of a saturated gravity wave spectrum in the mesosphere
EISCAT observations during MAC/SINE and MAC/Epsilon
The EISCAT incoherent scatter radar facility in Tromsoe, Norway was operated during the MAC/SINE campaign for 78 hours in the period 10 June to 17 July 1987, and during the MAC/Epsilon campaign for 90 hours in the period 15 October to 5 November 1987. The VHF (224 MHz) radar operations during MAC/SINE yielded most interesting observations of strong coherent echoes from the mesopause region. Characteristic data of these polar mesospheric summer echoes are presented. The UHF (933 MHz) radar operations during MAC/Epsilon were done with 18 deg off zenith beam and allows the deduction of meridonal and horizontal wind components as well as radial velocity spectra in addition to the usual electron density profiles in the D and lower E regions. Some results from the VHF and UHF radars indicating the presence of gravity waves are examined
Subtropical middle atmosphere dynamics observed by the Chung Li radar
The Chung Li Radar (24.91 N; 121.24 E) has been operating since 1986. A five beam observational configuration was used on a regular basis to study the various dynamics processes in the atmosphere-lower stratosphere height region. Due to its geographical location, the annual Typhoon and Mei-Yu seasons provide good opportunities to study the various interesting dynamic processes such as instabilities, generation of gravity waves, wave mean field interaction, etc. Three dimensional air motions due to these fronts are presented. Special cases of gravity wave generation, propagation and their effects on the turbulent layers are discussed
Preparing for the Unexpected: Recognizing a Tortuous Thoracic Aorta During Ultrasound-guided Thoracentesis
Ultrasound-guidance has become the standard of care for bedside thoracentesis. This manuscript describes the importance of utilizing point-of-care-ultrasound (POCUS) and color Doppler in avoiding an unusual, but potentially catastrophic aortic puncture during thoracentesis. The case describes a 70 year-old man who presented with one week of shortness of breath. He was found to have a large left-sided pleural effusion on imaging studies. During a bedside POCUS examination, he was found to have a hyperechoic linear structure in his posterior left hemithorax. Ultrasound application of color Doppler revealed a pulsatile flow, confirming visualization of the aorta. The site of needle insertion for thoracentesis was placed more laterally to avoid aortic puncture. The thoracentesis was performed successfully with removal of about 1000ml of sanguinous fluid. This clinical case demonstrates the importance of considering anatomic variants when performing a thoracentesis. As in this patient’s case, ultrasonography and color Doppler during thoracentesis can be useful in avoiding a potentially life-threatening puncture of the aorta
Bi-{Force}: {L}arge-scale bicluster editing and its application to gene expression data biclustering
Ultraviolet and visible photometry of asteroid (21) Lutetia using the Hubble Space Telescope
The asteroid (21) Lutetia is the target of a planned close encounter by the
Rosetta spacecraft in July 2010. To prepare for that flyby, Lutetia has been
extensively observed by a variety of astronomical facilities. We used the
Hubble Space Telescope (HST) to determine the albedo of Lutetia over a wide
wavelength range, extending from ~150 nm to ~700 nm. Using data from a variety
of HST filters and a ground-based visible light spectrum, we employed synthetic
photometry techniques to derive absolute fluxes for Lutetia. New results from
ground-based measurements of Lutetia's size and shape were used to convert the
absolute fluxes into albedos. We present our best model for the spectral energy
distribution of Lutetia over the wavelength range 120-800 nm. There appears to
be a steep drop in the albedo (by a factor of ~2) for wavelengths shorter than
~300 nm. Nevertheless, the far ultraviolet albedo of Lutetia (~10%) is
considerably larger than that of typical C-chondrite material (~4%). The
geometric albedo at 550 nm is 16.5 +/- 1%. Lutetia's reflectivity is not
consistent with a metal-dominated surface at infrared or radar wavelengths, and
its albedo at all wavelengths (UV-visibile-IR-radar) is larger than observed
for typical primitive, chondritic material. We derive a relatively high FUV
albedo of ~10%, a result that will be tested by observations with the Alice
spectrograph during the Rosetta flyby of Lutetia in July 2010.Comment: 14 pages, 2 tables, 8 figure
Ultraviolet Spectroscopy of Asteroid (4) Vesta
We report a comprehensive review of the UV-visible spectrum and rotational
lightcurve of Vesta combining new observations by Hubble Space Telescope and
Swift Gamma-ray Burst Observatory with archival International Ultraviolet
Explorer observations. The geometric albedos of Vesta from 220 nm to 953 nm are
derived by carefully comparing these observations from various instruments at
different times and observing geometries. Vesta has a rotationally averaged
geometric albedo of 0.09 at 250 nm, 0.14 at 300 nm, 0.26 at 373 nm, 0.38 at 673
nm, and 0.30 at 950 nm. The linear spectral slope as measured between 240 and
320 nm in the ultraviolet displays a sharp minimum near a sub-Earth longitude
of 20^{\circ}, and maximum in the eastern hemisphere. This is consistent with
the longitudinal distribution of the spectral slope in the visible wavelength.
The photometric uncertainty in the ultraviolet is ~20%, and in the visible
wavelengths it is better than 10%. The amplitude of Vesta's rotational
lightcurves is ~10% throughout the range of wavelengths we observed, but is
smaller at 950 nm (~6%) near the 1-\mum band center. Contrary to earlier
reports, we found no evidence for any difference between the phasing of the
ultraviolet and visible/near-infrared lightcurves with respect to sub-Earth
longitude. Vesta's average spectrum between 220 and 950 nm can well be
described by measured reflectance spectra of fine particle howardite-like
materials of basaltic achondrite meteorites. Combining this with the in-phase
behavior of the ultraviolet, visible, and near-infrared lightcurves, and the
spectral slopes with respect to the rotational phase, we conclude that there is
no global ultraviolet/visible reversal on Vesta. Consequently, this implies a
lack of global space weathering on Vesta, as previously inferred from
visible-near-infrared data.Comment: 44 pages, 5 figures, 1 tabl
Effectiveness of progressive muscle relaxation, deep breathing, and guided imagery in promoting psychological and physiological states of relaxation
Research suggests that multiple forms of relaxation training (e.g., progressive muscle relaxation, meditation, breathing exercises, visualization, and autogenics) can help individuals reduce stress, enhance relaxation states, and improve overall well-being. We examined three different, commonly used approaches to stress relaxation—progressive muscle relaxation, deep breathing, and guided imagery—and evaluated them in a head-to-head comparison against each other and a control condition. Sixty healthy undergraduate participants were randomized to one of the four conditions and completed 20 minutes of progressive muscle relaxation, deep breathing, or guided imagery training that was delivered by recorded audio instruction. Baseline and follow-up assessment of psychological relaxation states were completed. Physiological relaxation was also assessed continuously using measures of electrodermal activity and heart rate. Results showed that progressive muscle relaxation, deep breathing, and guided imagery all increased the state of relaxation for participants in those groups, compared to participants in the control group. In each case, the increase was statistically significant and although the groups did not differ on relaxation before training, all groups were significantly higher on relaxation after training, as compared to the control group. Progressive muscle relaxation and guided imagery showed an immediate linear trend toward physiological relaxation, compared to the control group, and the deep breathing group showed an immediate increase in physiological arousal followed quickly by a return to initial levels. Our results lend support to the body of research showing that stress relaxation training can be effective in improving relaxation states at both the psychological and physiological level. Future research could examine stress relaxation techniques in a similar manner using designs where multiple techniques can be compared in the same samples
Swift UVOT Grism Spectroscopy of Comets: A First Application to C/2007 N3 (Lulin)
We observed comet C/2007 N3 (Lulin) twice on UT 28 January 2009, using the UV
grism of the Ultraviolet and Optical Telescope (UVOT) on board the Swift Gamma
Ray Burst space observatory. Grism spectroscopy provides spatially resolved
spectroscopy over large apertures for faint objects. We developed a novel
methodology to analyze grism observations of comets, and applied a Haser comet
model to extract production rates of OH, CS, NH, CN, C3, C2, and dust. The
water production rates retrieved from two visits on this date were and 7.9 0.7 x 1E28 molecules s-1, respectively. Jets were sought
(but not found) in the white-light and `OH' images reported here, suggesting
that the jets reported by Knight and Schleicher (2009) are unique to CN. Based
on the abundances of its carbon-bearing species, comet Lulin is `typical'
(i.e., not `depleted') in its composition
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